Pressure sensors, or transducers, sense absolute or differential pressure and produce a corresponding output signal. The pressure sensors may, for example, use differential capacitors or electromechanical mechanisms as sensing elements. The current invention uses a magnetic fluid as the sensing element.
A prior pressure transducer uses a magnetic fluid in a tube disposed in a strong magnetic field. In essence the fluid functions as a diaphragm, or membrane, that deforms in response to changes in the differential pressure at opposite ends of the tube. The resulting changes in the shape of the fluid membrane are converted to an electrical output indicative of the differential pressure.
The use of a magnetic fluid as the sensing element has certain advantages. The magnetic fluid is essentially free of static frictional forces, which tend to introduce inaccuracies into sensors with electromechanical mechanisms. Further, the magnetic fluid is not damaged by pressures above the pressure capacity of the sensor. The invention utilizes a magnetic fluid sensing element in a manner that is not contemplated by known prior sensors.